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J Orthop Res. 2014 Mar;32(3):448-54. doi: 10.1002/jor.22523. Epub 2013 Nov 19.

Inhibition of cell-matrix adhesions prevents cartilage chondrocyte death following impact injury.

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  • 1Department of Orthopaedics and Rehabilitation, The University of Iowa, Iowa City, Iowa; Department of Biomedical Engineering, The University of Iowa, Iowa City, Iowa.

Abstract

Focal adhesions are transmembrane protein complexes that attach chondrocytes to the pericellular cartilage matrix and in turn, are linked to intracellular organelles via cytoskeleton. We previously found that excessive compression of articular cartilage leads to cytoskeleton-dependent chondrocyte death. Here we tested the hypothesis that this process also requires integrin activation and signaling via focal adhesion kinase (FAK) and Src family kinase (SFK). Osteochondral explants were treated with FAK and SFK inhibitors (FAKi, SFKi, respectively) for 2 h and then subjected to a death-inducing impact load. Chondrocyte viability was assessed by confocal microscopy immediately and at 24 h post-impact. With no treatment immediate post-impact viability was 59%. Treatment with 10 µM SFKi, 10 μM, or 100 µM FAKi improved viability to 80%, 77%, and 82%, respectively (p < 0.05). After 24 h viability declined to 34% in controls, 48% with 10 µM SFKi, 45% with 10 µM FAKi, and 56% with 100 µM FAKi (p < 0.01) treatment. These results confirmed that most of the acute chondrocyte mortality was FAK- and SFK-dependent, which implicates integrin-cytoskeleton interactions in the death signaling pathway. Together with previous findings, these data support the hypothesis that the excessive tissue strains accompanying impact loading induce death via a pathway initiated by strain on cell adhesion receptors.

© 2013 Orthopaedic Research Society. Published by Wiley Periodicals, Inc.

KEYWORDS:

articular cartilage; chondrocytes; focal adhesions; integrins; posttraumatic osteoarthritis (PTOA)

PMID:
24249698
[PubMed - indexed for MEDLINE]
PMCID:
PMC4034578
Free PMC Article
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